Fluid heater



} IN VEN TOR. coumz/wor 05mm I @hW ATTORNEY June 20, 1939. c. F. DENNEY FLUID HEATER Filed May 5, 1955 Patented June 20, 1939.

PATENT OFFICE FLUID Courtlandt F. Denney,

to Foster Wheeler HEATER Westfield, N. J., assignor Corporation, New York,

N. Y., a corporation of New York Application May 3,

3 Claims.

This invention relates to fluid heaters and more particularly pertains to tubular heaters for heating fluids such as hydrocarbon oils and the like.

Prior types of tubular heaters or tube stills are in general arranged with a fire chamber or furnace in which the products of combustion are produced and which is usually a radiant heat absorption section, and a convection section which is separated from the furnace by means of a solid or air-cooled bridge wall. one or more tube banks are disposed under and adjacent the roof of the furnace, and in some types tubes are disposed adjacent the floor and The gases in these stills flow through the furnace from the burners toward and over the top of the bridge wall and thence over the tubes in the convection section to the flue or stack connected 0 with the still. The gases in flowing through the furnace or fire chamber are not equally distributed throughout the furnace and the gases tend to concentrate directly over the bridge wall and in the area adjacent thereto in the furnace with the result that some of the tubes in the one or more tube banks disposed in the furnace tend to become overheated while other tubes of these banks do not receive sufficient heat. In consequence, the fluid flowing through the tubes is unequally heated and overheated and with hydrocarbon oils, decomposition results. Also in prior types of tube stills, the velocity of the gases flowing through the furnace is usually so low thatv eddy currents are formed which increases the tendency toward unequal heating in various sections of the Several tube banks. Additionally, the absorption of heat through the walls of the furnace is ordinarily so large as to seriously affect the overall efficiency of the stills.

The present invention overcomes the aforementioned and other disadvantages of prior types of tube stills, and provides a fluid heater in which the gases flowing through the furnace or 55 reduced as compared with prior types of heaters.

In these stills,

adjacent one or more of the walls of the furnace.

1935, Serial No. 19,635

Other advantages of the invention include great overall efiiciency, and low initial cost, and low cost of operation.

The nature of the invention, including its objects and the advantages thereof, will be understood from the following description considered in connection with the accompanying drawing, forming a part thereof and in which:

Fig. 1 is a. vertical longitudinal sectional view of a tube still embodying the invention, and

Fig. 2 is a partial vertical sectional view, taken on line 2-2 of Fig. 1.

Like characters of reference refer to the same 01 similar parts throughout the several views.

The form of the invention selected for illustration is embodied in'a tube still having a plurality of furnaces in which the fluid to be heated passes through the convection section and the several furnaces or fire chambers in series, an arrangement which is particularly adaptable to the cracking of hydrocarbon oils. will be understood that the invention is not limited tothe particular form shown, but that the several forms may be embodied, for example, in fluid heaters having a single furnace, or in heaters having a plurality of furnaces wherein the fluid to be heated passes in parallel through the several furnaces or in series through some of the furnaces and in parallel through others, or in heaters which heat two or more fluids at the same time.

Referring to the drawing, the tube still illustrated has two opposed fire chambers or furnaces l0 and II which are spaced by a chamber l2 and a convection section l3 disposed immediatelyabove the chamber l2 and at a level above the roofs of the fire chambers. Each of the fire chambers or furnaces has a front wall l4, a rear wall l5, a roof l6 and a floor H. The still is provided with a suitable roof l8. The convection section I3 is provided with a bank of convection heating tubes l9 and in the em-.

However, it

bodiment shown, each of the furnaces l0 and II is provided with a bank of roof tubes 20 and a bank of floor-tubes 2|. The roof tubes are supported by suitable means designated 22 which depend from the framework of the roof l8 of the still, and the floor tubes 2| are supported by suitable means 23 resting on or secured to the floor H. The fluid to be heated'enters the inlet 24 at the upper end of the convection bank l9 and after passing therethrough is conducted through pipe 25 to the fioor tubes 2| in furnace l0. After flowing therethrough the fluid is conducted through pipe 26 to the roof tubes 20 of furnace Ill and after flowing therethrough, the fluid is transferred through pipe 21 to the roof tubes of the furnace II, thence through pipe 28 to and through the floor tubes of furnace H and is discharged through the still outlet 29. The roof or the floor tube bank in either or both furnaces may be omitted and the tube banks may be disposed along one or more of the side and end walls, if desired.

Products of combustion are produced in the furnace by means of one or more burners 30 which may burn either pulverized coal, oil or gas or combinations thereof. The products of combustion produced by the burners 30 flow from the front wall of each furnace toward and through the rear walls IS. The wall I5 of each furnace is provided with a plurality of gas passages 3|, preferably throughout substantially the entire extent of the wall. In the form shown in Figs. 1 and 2, these passages 3| have smaller cross-sectional areas or smallerrflow areas at the upper portion of the wall than at the lower portion and the passages disposed intermediate the upper and lower portions of the walls are of gradually increasing cross-sectional or flow area from the upper to the lower portions of thewalls. With this arrangement, greater resistance to the flow of the gases through the upper portion of the wall is provided than through the lower portion, or in other words, the resistance to flow of the gases through the wall gradually diminishes from the top to the bottom of the wall. The gases flowing through the walls l5 enter the chamber l2 and flow upwardly therethrough and therefrom'into and through the convection chamber I3 and out through flue 32 controlled by a damper 33 to a stack. With the convection section disposed as disclosed, underground flues are not required.

By utilizing walls of the character of walls l5, it will be perceived that the gases in flowing through the furnace are caused to be substantially uniformly distributed throughout the entire transverse cross-sectional areas of the furnace, or in other words, are substantially uniformly distributed throughout the furnace in directions transverse to the direction of flow of the gases. Accordingly, there is no tendency for the gases to concentrate at any one point or area in the furnace and all of the tubes of the roof tube bank and/or the floor tube bank are substantially uniformly heated in consequence of which the fluid flowing through either or both of these tube banks will be uniformly heated with no danger of overheating or decomposition. The sizes of the passages 3| shown in Figs. 1 and 2 are merely illustrative. The flow areas of these passages may be varied as desired for the purpose.

As clearly shown, the side and end walls of the furnaces l0. and l I are materially lower than the corresponding walls in prior types of tube stills. As a result, the roof and floor of each of the furnaces are much closer than in prior tube stills, in consequence of which the furnace volume is materially less and the velocity of the gases flowing through the furnaces is materially greater than in prior stills. As indicated,. the burner or burners 30 are disposed substantially equidistantly from the roof and floor of the furnace and the roof and floor tube banks which contributes toward the equal distribution of the gases in their flow through thefurnace. That section of the roof bank which is disposed over the burners will receive more heat than in prior high wall designs of heaters because of their closer proximity to the burners which results in greater absorption of radiant heat. In consequence of this greater absorption of heat in the section of the roof tube bank immediately above the burners, the heat absorbed by the section of the floor tube bank immediately under the burners will-be less than with the prior high wall types of stills. Because of the smaller furnace volume and the resulting higher velocity of the gases in flowing. through the furnace, the tendency for eddy currents to form will be less than in the high wall types. The higher gas velocity will also provide better control over the heat distribution to the various parts of the radiant section or sections of the still. Since the surface area of the enclosing walls of the low wall type of still is less than the prior types, radiation losses from the setting will be much reduced. Accordingly, it will be possible to bring the unit on stream in less time and it will cool off more quickly when shut down. The initial cost of a low wall type of still will be considerably less and maintenance costs will also be reduced.

Ordinarily, the roof and floor of the furnace will be spaced apart a distance which is just sufflcient to prevent flame impingement on the roof or floor tube banks. Otherwise expressed, the roof and floor should be disposed as close together as possible without obtaining impingement of the burner flame on either the roof or floor tube bank. With a single burner, or a single hori-.

zontal row of burners substantially equidistantly spaced from the roof and floor tube banks, the latter ordinarily should be spaced apart a distance in the range of approximately 6 to 10 feet, with the roof and floor spaced to support the banks at the desired distance apart in this range. Where a plurality of rows of tubes are employed, the lowermost tube row of the'roof bank and the uppermost tube row of the floor bank should be spaced apart a distance within this range so as to prevent flame impingement on the tubes. Capacity may be varied by varying the width of the furnace.

The following example will serve to indi ate suitable proportions for a tube still embod mg the invention. Assume that the still is of the general arrangement shown in Fig. 1 with series flow through the convection section, the lefthand furnace as seen in Fig. 1 and the righthand furnace and with a single row of roof and floor tubes respectively in the left-hand furnace and a double rowof superposed roof and floor tubes respectively in the right-hand furnace. The tube banks in the left-hand furnace may be spaced 9 feet 4 inches apart on their center lines, and in the right-hand furnace, the lower row of roof tubes and the upper row of floor tubes may be spaced 8 feet apart on their center lines. The tube banks in the left-hand furnace may be 14 feet 2 inches long and the tube banks in the right-hand furnace may be 10 feet 8 inches long. The roof, floor, side and end walls of the furnace should be spaced apart a distance sufficient to accommodate the tube banks at suitable distances from the roof, floor and walls. It will be understood that these dimensions are merely illustrative and that the invention is not to be limited w thereto.

Inasmuch as changes may be made in the form, location and arrangement of the several parts of the tube stills herein disclosed without departing from the principles of the invention, no intention. is entertained to limit the invention except by the scope of the appended claims.u her without material concentration of the gases.

What is claimed is: I

' 1. A fluid heater having a fire chamber, a bank of fluid heating tubes adjacent the roof and floor of the fire chamber, one or more burners disposed in a wall of the ilre chamber substantially equidistantly from the, roof and floor tube bank, said tube banks being spaced apart a distance no greater than necessary to prevent flame impingement on the tube banks, and a wall op-.

positely disposed with respect to the burner wall and having a plurality of gas passages therein proportioned with. respect to flow area to provide substantially equal distribution of the gases in their flow through the chamber. 2. -A fluid heater comprising a fire chambe having tom-bottom and side walls, a plurality of banks of fluid heating tubes disposed solely adportion of the wall having smaller flow areas than the passages in the lower portion of the wall 'to provide distribution of the gases throughout substantially the entire flow area of the chemin any part of said flow area.

3. A fluid heater comprising a fire chamber having top, bottom and side walls, a plurality of banks of fluid heating tubes disposed solely adjacent at least one of said walls of the chamber andarrangedto be heated principally by heat radiated, from the gases in the chamber, and means including a wall of the chamber having gas passages therein through which the gases pass on leaving the chamber, a flue for the heater into which the gases pass subsequent to their passage through the wall, the arrangement being such that there is a greater tendency for the gases to flow through one portion of the wall than through other portions, said wall passages being proportioned with respect to resistance to flow of said gases therethrough' by providing graduated difierences in flow areas of certain. of the wall passages to provide distribution of the gases throughout substantially the entire flow area of the chamber without material concentra tion of the gases in any part of said flow area, the resistanceto flow of the gases through said one portion of the wall being greater than through other portions. v

COURTLANDT r. DENNEY. 

